Cyclone furnace



April 20, 1965 M. M. CLARK ETAL 4 3,179,074

CYCLONE FURNACE Filed Feb. 21, 1962 3 Sheets-Sheet 1 INVENTORS Merle M. Clark Nlcholas P Rpsanowsky Wa e L. Sage BYW ATTORNEY April 20, 1965 M. M. CLARK ETAL CYCLONE FURNACE 3 Sheets-Sheet 2 Filed Feb. 21 1962 ATTORNEY April 20, 1965 I M. M. CLARK ETAL 3,179,074

CYCLONE FURNACE Filed Feb. 21, 1962 s Sheets-Sheet 3 INVENTORS Merle M. Clark Nlcholas P. Rgsanowsky Wa e L. Sage W ATTORNEY 3,179,074 CYCLONE FURNACE Merle M. Clark, Barberton, Nicholas P. Rusanowsky, Akron, and Warnie L. Sage, Louisville, Ohio, assignors to The Eabcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Feb. 21, 1962, Ser. No. 174,914 8 Claims. (Cl. 11028) The present invention relates in general to the construction and operation of apparatus for burning ash-containing solid fuel, and more particularly, to improvements in the construction and operation of the provisions for introducing fuel and air into the combustion chamber of a cyclone type furnace designed for the burning of an ashcontaining crushed or granular fuel above the fuel ash fusion temperature. Furnaces of this general type are described in U.S. Patent Nos. 2,594,312 and 2,971,840. 7

One of the principal disadvantages of prior cyclone furnace fuel feeding systems is that they must operate against the high static pressure of the carrier or primary air stream entering the cyclone furnace with the fuel in suspension. This imposes rigid requirements on the fuel feeder seal and/or necessitates a relatively high head of fuel to counteract the primary air pressure and thereby prevent infiltration of the hot, high pressure primary air into the fuel supply conduit and bunker. In addition, fuel feeding systems including a large head of fuel for air sealing purposes have afforded some difficulty in the past in that the particulate fuel has a tendency to bridge across the fuel supply conduit, with consequent fuel feeding interruptions. Fuel feeding systems of this type are shown in the aforesaid patents. In such a system coal from a bunker is supplied to a feeder by gravity and at the feeder dis charge is joined by a supply of hot, high pressure primary air. After the feeder the primary air stream and fuel in suspension pass through a conduit for discharge at high velocity tangentially into a circular primary air-fuel inlet chamber or primary burner opening to one end of the combustion chamber. The primary air is normally supplied to the discharge of the feeder at a pressure of about 40 inches of water. The feeder itself does not provide a seal against this hot, high pressure primary air to keep it from flowing through the coal supply conduit into the bunker. This must be done by providing a suflicient head of coal above the feeder and/or by providing a mechanical seal directly after the feeder. In addition it has been found that by introducing the primary air and fuel together into the primary burner at high velocity, the inner wear block surfaces lining the burner require replacement after relatively short periods of service. Some difficulty has also been encountered by the recirculation of whirling burning fuel particles from the combustion chamber into the primary burner, with consequent overheating and burning of parts of the primary burner.

The foregoing problems are eliminated, in accordance with the invention, by special provisions for the introduction of fuel and air into the combustion chamber. The present invention provides for a primary burner of circular cross-section opening to one end of the combustion chamber of a cyclone furnace and constructed and arranged for the separate introduction of a stream of primary air and a stream of slag-forming particle fuel tangentially into the burner at locations between the opposite ends thereof, while a stream of tertiary air is introduced into the front end of the primary burner at a position inwardly and axially of the whirling streams of primary air and fuel entering the burner. This system of fuel and air supply to the primary burner of the cyclone furnace minimizes the head of fuel required to effectively check infiltration of hot, high pressure combustion air into the fuel supply system, permits elimination of the fuel feeder mechanical seals formerly required for this purpose, reduces wear of the primary burner since the fuel may be intro duced therein at lower velocities, and prevents recirculation of burning fuel particles from the combustion chamber to the primary burner.

The various features of novelty which characterize our invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which we have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a partly diagrammatic sectional elevation of a cyclone furnace having an air and fuel inlet chamber constructed and arranged in accordance with our invention;

FIG. 2 is a front view of the cyclone furnace of FIG. 1;

FIG. 3 is an enlarged sectional elevation of the air and fuel chamber of FIG. 1 taken along the line 3--3 of FIG. 5;

FIG. 4 is a vertical section taken along the line 44 of FIG. 3;

FIG. 5 is a plan view, partly broken away, of the air and fuel inlet chamber of FIG. 3;

FIG. 6 is a fragmentary vertical section taken along the line 6-6 of FIG. 5;

FIG. 7 is a fragmentary vertical section taken along line 7-7 of FIG. 5; and

FIG. 8 is a fragmentary front view taken alOng line 8--S of FIG. 5.

The steam generating unit illustrated in part in FIG. 1 comprises as its main parts a cyclone type furnace 10 which is fired by a crushed or granular fuel, such as bituminous or semi-bituminous coal. The products of combustion from the cyclone furnace flow into a secondary furnace chamber containing a reflecting arch 13 and slag screen 13A with which the products of combustion successively contact. The gaseous products of combustion flow upwardly in the secondary furnace to a convection heating section of the unit, not shown.

With reference to FIGS. 1 and 2, the cyclone furnace 10 comprises a horizontally elongated combustion chamber 14 of substantially circular cross-section, the circular boundary wall being formed by closely spaced studded tubes 15 covered by a layer of refractory material, each tube having a semi-circular bent portion and adjacent tubes having their bent portions oppositely arranged to form the circumferential Wall. The lower ends of the wall tubes are connected to interconnected supply headers 16 and their upper ends to a discharge header 17. The cyclone furnace is preferably set with its longitudinal axis at a slight angle to the horizontal to facilitate draining of molten slag into the secondary furnace. The outer end portion of the cyclone furnace is tapered outwardly in cross-section and formed by closely spaced circular studded tubes 18 of progressively smaller bend diameter connected to a make-up header 19 and a riser header 20, the latter being connected to the discharge header 17. The circular tubes 18 thus form a double frusto-conical section symmetrically arranged relative to the combustion chamber axis.

Combustion chamber wall tubes 15 along one side are bent radially outwardly along an involute curve for a major portion of the combustion chamber length start ing at the inner end of the tapering portion of the chamber, while the corresponding tubes along the opposite side are bent outwardly and connected to an intermediate outlet header 21, thus cooperating to define an axially elongated secondary air inlet port 22. The header 21 is connected to the discharge header 17 by riser tubes 23.

A main air duct 24 of substantially rectangular cross-sec tion leading from a forced draft fan, not shown, terminates in a transversely tapering curved section opening to the secondary air port 22. The lower portion of the duct 24 is subdivided by vertical partitions into a series of side-by-side sections extending longitudinally of the furnace chamber. Each duct section is provided with a damper for controlling the velocity of the corresponding secondary air stream while maintaining the entering air stream at all times along the combustion chamber Wall.

The rear end of the combustion chamber 14 is partly closed by a fluid cooled wall 79 having a gas outlet 71 in the form of a re-entrant throat 72 arranged therein concentric with the combustion chamber axis. A slag outlet 73 is formed in the wall 76* at a position below the throat 72 for the continuous discharge of molten slag. The wall 70 forms part of the fluid cooled boundary walls of the secondary furnace chamber 11. It is to be understood that the portions of the fluid circulation system described are suitably connected into the natural circulation system of the steam generating unit.

In accordance with the invention, an air and fuel inlet chamber or primary burner 25 of substantially circular cross-section and of smaller diameter than the combus tion chamber 14 is arranged at the front end of and concentrically opens to the combustion chamber, the cir cular boundary wall of the chamber 25 being formed by a plate 26 lined in most part with replaceable Wearresistant metallic blocks 27 and having its rear end provided with a flange 28 suitably connected to the front end of the combustion chamber 14. Boundary wall 26 is surrounded by a circular plate 29 and cooperates therewith to form an annular passage 30 for the flow of cooling water having inlet and outlet pipe connections 31 and 32 opening through the plate 29.

The front end of the chamber is normally closed by a circular cover 34 secured by nuts 35 to circumferen tially spaced threaded studs 36 welded to the outer surface of the front end of the plate 26. Cover 34 is pivot ally supported by a hinge assembly comprising pairs of vertically spaced and aligned lugs 38 and 39 respectively secured to and projecting laterally from the outer surface of the cover 34 and the circular plate 29, with a pivot pin 41 connecting the lugs 38 to one end of each of a pair of vertically spaced and aligned hinge members 42, a pivot pin 43 connecting the lugs 39 to one end of each of a pair of vertically aligned and spaced hinge members 44, and a pivot pin 45 connecting the opposite ends of the hinge members 42 and 44 to each other, and with each pair of hinge members 42 and 44 being braced by a vertical bar 46 extending between and secured by welding to the corresponding pair of hinge members. A pair of handles 47 are provided on the outer surface of the cover to facilitate the opening and closing thereof. Thus complete and quick access to the chamber 25 and inspection, repair or replacement of the wear blocks therein may be had by means of the hinged cover 34.

A circular plate 48 of slightly smaller diameter than the plate 26 is disposed parallel to and spaced inwardly from the cover 34, is secured to the inner surface of the cover by an annular plate member 49, and cooperates with the cover and plate 49 to form a passage 51 for the flow of cooling water, with the passage 51 being supplied with water by a pipe connection 52 opening through the cover, and with the water supplied to the passage 51 subsequently flowing through a pipe 53 leading from the passage 51 to the inlet pipe connection 31 for the passage 39 and thence through the passage 30 to the outlet 32. Inspection of the burner during operation is provided by a downwardly inclined inspection port 54 projecting through the cover 34 and plate'48 in sealing relation therewith. In the event firing of oil or gas is desired the central portion of the cover 34 is formed with an opening fitted with a blind flange 55 which may be opened for the insertion of an oil or gas burner.

The cover 34 is also provided with a circular plate- 56 of slightly smaller diameter than the plate 26 extending parallel to and spaced inwardly from the cover and the plate 48, formed with a central orifice 57 concentric with the chamber 25, and secured by studs 58 to the inner surface of the cover. When the cover is in its closed or operative position the plate 56 sub-divides the chamber 25 to provide a tertiary air supply chamber 25A and a primary air supply chamber 258. Air is supplied to the chambers 25A and 25B by a horizontal duct 59 extending along the length of the upper portion of the plate 26 and sub-divided by a vertical partition 61 form ing, in eifect, an extension of the plate 56 when the cover is in its closed position and providing tertiary and pri mary air supply ducts 59A and 59B respectively opening;

substantially tangentially into and supplying air to the chambers 25A and 258, with the duct 59A extending along almost the entire length of the chamber 25A and the duct 59B extending along about three fourths of the length of the chamber 2513. Air supply to the ducts 59A and 59B is provided by a forced draft fan, not shown,v by way of a branch duct, not shown, connected at oneend to the main duct 24 and at its opposite end to the duct 59.

As shown in FIGS. 3 and 4, the wear blocks 27 line only that portion of the plate 26 forming the circumferential wall of the chamber 25B and are secured by studs and nuts to the plate 29. Each of the wear blocks extends the full length of the chamber 253 and has an arc-shaped inner surface so formed that the leading edge of the block projects inwardly of the chamber 25B a slightly greater distance than the trailing edge of the next adjacent block in a clockwise direction to the end of minimizing wear of the blocks.

As shown in FIGS. 3, 5 and 6 the effective flow area of each of the ducts 59A and 59B, and thus the velocity pressure and quantity of the tertiary and primary air streams respectively discharging to the chambers 25A and 25B, is controllable without changing the position of the entering air streams relative to the circumferential wall of these chambers by means of plate dampers 62A and 623. Each plate damper is mounted on a shaft 63 and is manually adjusted and operated by a ratchet wrench applied to a shaft 64 carrying a worm gear 65 arranged to mesh with a worm wheel 66 mounted on the outer end of the shaft 63.

Coal, in crushed or granulated form, is gravitationally introduced at low velocity into the upper portion of the chamber 25B by Way of a vertical conduit 67 having its axis arranged normal to the axis of the duct 59B and opening substantially tangentially into the chamber 253 at a position intermediate the length of and circumferentially spaced from the discharge end of the duct 59B. The conduit 67 is disposed within and welded in sealing relation to a circular sleeve 68 extending through and welded to the plates 26 and 29, with the conduit 67 hav ing its upper end formed with a flange 69 for connection to the fuel supply system.

In the operation of the cyclone furnace and air and fuel supply construction described, preheated air is supplied to the main air duct 24 at a high positive pressure and split into three streams, 15-20% being used as primary air, -80% as secondary air, and 35% as tertiary air. The total air supply preferably ranges between -115% of the theoretical combustion requirements. The primary air tangentially enters the chamber 253 in a high velocity axially elongated stream and whirls along the circumferential wall thereof, while the crushed fuel is separately and tangentially and gravitationally introduced into the chamber 253 into and in the same direction of rotation as the primary air and at a velocity considerably lower than the velocity of the entering primary air. At the same time, the whirling stream of tertiary air supplied by the duct 59A to the chamber 25A is directed axially of and into the chamber 25B by the orifice plate :56. Under maximum continuous load operating condi= :tions, the pressure of the primary air flowing to the duct 59B is usually about 35 inches of water, while the pres= sure of the primary air whirling along and adjacent to the circumferential Wall of the chamber 25B is around 15 inches of water due to the pressure drop occasioned in flowing through the duct 59B and in entering the chamber 25B. The pressures of the tertiary air entering the duct 59A and whirling in the chamber 25A are substantially the same as those of the primary air at corresponding locations, that is, at the entrance to the duct 59B and in the chamber 25B, with the tertiary air having a pressure of about inches of water entering the chamber 25B due to pressure drop in flowing through the orifice 57. Thus by separately supplying the fuel and primary air to the chamber 25B, the fuel sealing head for prevention of air infiltration need be sufficient to counteract a pressure of only inches of water and the mechanical seal formerly required in the fuel supply system to counteract primary air pressure may be eliminated. Reduction in the head of fuel required to check infiltration of high pressure combustion air into the fuel supply system permits a corresponding reduction in the coal bunker head room requirements heretofore necessary for fuel sealing or for the installation of a mechanical seal, with resultant saving in building costs. Moreover, the gravitational introduction of fuel into the chamber B at a velocity considerably lower than the velocity of the entering primary air, results in considerably less wear of the chamber 25B and particularly of the blocks 27 therein.

With the primary and tertiary ai-r streams and the fuel so introduced to the compartments of the chamber 25, the entering fuel particles are picked up by and axially advance with the whirling primary air stream through the chamber 25B to the combustion chamber 14, While the whirling tertiary air passes through the central portion of the chamber 25B axially and inwardly of the whirling stream of primary air and fuel entering the combustion chamber 14. The primary air fuel mixture enters the combustion chamber 14 in a stream whirling in a clockwise direotion with the inner coreof tertiary air entering in the same direction.

The streams of high velocity secondary air discharging from the secondary air ports 22 tangentially enter the combustion chamber 14 in the same direction of rotation and at the outer side of the whirling stream of primary air and fuel. Combustion of the fuel progresses at a high rate, with a gradual mixing of the secondary air streams with the enclosed streams of primary air and fuel. Combustion proceeds at a rate suflicient to maintain a normal mean temperature in the combustion chamber over a wide range of operation substantially above the fuel ash fusion temperature. Under such combustion conditions the ash content of the fuel is rapidly reduced to a molten condition and due to the centrifugal effect thereon, the combustion chamber walls will rapidly coat with a film of molten slag which adheres to the refractory inner face of thewalls and provides a sticky surface against which fuel particles are thrown and to which they adhere. The high velocity of the burning fuel-air mixture causes the gas stream to follow a helical path to the rear of the combustion chamber Where the gas is caused to reverse direction before entering the gas outlet 71. The gas flow reversing action is effected by an annular pocket 74 and facilitates the separation of suspended slag particles from the outgoing gases. The tertiary air is introduced on the inward side of the whirling mass of burning fuel to mix with the fine fuel particles that are not thrown to the periphery of the combustion chamber and to prevent recirculation of burning particles back into the chamber 2513, {thereby assuring combustion of the fine fuel particles and preventing damage by overheating or burning of the parts ,of the chamber 25B. Molten slag resulting from combustion continuously discharges through the outlet 73 into the secondary furnace chamber 11 for fiow therefrom to a slag tank, not shown. The gases discharged through the outlet 71 contain little, if any, combustibles, combustion of the fuel being substantially completed in the combustion chamber.

While in accordance with the provisions of the statutes we have illustrated and described herein the best form and mode of operation of the invention now known to us, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. A cyclone furnace having walls defining a combustion chamber of substantially circular cross-section, fluid cooling means for said walls, means forming a restricted gas outlet at one end of said chamber, means forming a substantially unobstructed air and fuel inlet chamber of substantially circular cross-section and of smaller diameter than and opening at one end into the opposite end of said combustion chamber, means for introducing a low velocity stream of slag-forming particle fuel into said air and fuel inlet chamber at a position between the opposite ends thereof, means for introducing a high velocity stream of primary air tangentially into said air and fuel inlet chamber at a location between the opposite ends thereof and separate from the point of fuel entry and effecting a whirling path of travel therein with the incoming fuel particles along the circumferential wall of said air and fuel inlet chamber, means for introducing a stream of secondary air into said combustion chamber tangentially to the circumferential wall thereof at a location between the point of fuel entry and the gas outlet, means for introducing a stream of tertiary air into the opposite end of said air and fuel inlet chamber at a position inwardly and axially of and separate from the streams of primary air and fuel entering said air and fuel inlet chamber, and a slag outlet in the lower part of said combustion chamber.

2. A cyclone furnace having walls defining a combustion chamber of substantially circular cross-section, fluid cooling means for said walls, means forming a restricted gas outlet at one end of said chamber, means forming a substantially unobstructed air and fuel inlet chamber of substantially circular cross-section and of smaller diameter than and opening at one end into the opposite end of said combustion chamber, means for separately introducing a stream of primary air and a stream of slag-forming particle fuel tangentially into said air and fuel inlet chamber at locations between the opposite ends thereof and effecting a helical path of travel therein along the circumferential wall of said air and fuel inlet chamber, means for introducing a stream of secondary air into said combustion chamber tangentially to the circumferential Wall thereof at a location between the point of fuel entry and the gas outlet, means for introducing a stream of tertiary air into the opposite end of said air and fuel inlet chamber at a position inwardly and axially of and separate from the whirling streams of primary air and fuel entering said air and fuel inlet chamber, and a slag outlet in the lower part of said combustion chamber.

3. A cyclone furnace having walls defining a combustion chamber of substantially circular cross-section, fluid cooling means for said walls, means forming a restricted gas outlet at one end of said chamber, means forming a substantially unobstructed air and fuel inlet chamber of substantially circular cross-section and of smaller diameter than and opening at one end into the opposite end of said combustion chamber, means for gravitationally introducing slag-forming particle fuel tangentially into said air and fuel inlet chamber at a position between the opposite ends thereof, means for introducing a high velocity stream of primary air tangentially into said air and fuel inlet chamber in the same angular direction as the incoming fuel at a location between the opposite ends of the air and fuel inlet chamber and separate from the point of fuel entry and effecting a whirling path of travel therein with the incoming fuel particles along the circumferential Wall of said air and fuel inlet chamber, means for introducing a stream of secondary air into said combustion chamber tangentially to the circumferential wall thereof at a location between the point of fuel entry and the gas outlet, means for introducing a stream of tertiary air into the opposite end of said air and fuel inlet chamber at a position inwardly and axially of and separate from the streams of primary air and fuel entering air and fuel inlet chamber, and a slag outlet in the lower part of said combustion chamber.

4. A cyclone furnace having walls defining a combustion chamber of substantially circular cross-section, fluid cooling means for said walls, means forming a restricted gas outlet at one end of said chamber, means forming an air and fuel inlet chamber of substantially circular crosssection and of smaller diameter than and opening at one end into the opposite end of said combustion chamber, a circular plate in said air and fuel inlet chamber at a position intermediate the opposite ends thereof subdividing said air and fuel inlet chamber into a tertiary air inlet compartment and a substantially unobstructed primary air and fuel inlet compartment and formed with an orifice opening from the tertiary air compartment to the primary air and fuel compartment at a position inwardly of the circumferential wall of said primary air and fuel compartment, means for introducing slag-forming particle fuel into said primary air and fuel compartment at a position between the opposite ends thereof, means for introducing a high velocity stream of primary air tangentially into said primary air and fuel compartment at a location between the opposite ends thereof and separate from the point of fuel entry and effecting a whirling path of travel therein with the incoming fuel particles along the circumferential wall of said primary air and fuel compartment, means for introducing a stream of secondary air into said combustion chamber tangentially to the circumferential wall thereof at a location between the point of fuel entry and the gas outlet, means for introducing a stream of tertiary air into said tertiary air compartment and effecting a flow therethrough to and through said orifice and primary air and fuel compartment inwardly and axially of the streams of primary air and fuel entering said primary air and fuel inlet compartment, and a slag outlet in the lower part of said combustion chamber.

5. A cyclone furnace having walls defining a combus tion chamber of substantially circular cross-section, fluid cooling means for said walls, means forming a restricted gas outlet at one end of said chamber, means forming an air and fuel inlet chamber of substantially circular crosssection and of smaller diameter than and opening at one endinto the opposite end of said combustion chamber, a cover pivotally connected to and normally closing the opposite end of said air and fuel inlet chamber, a circular plate in said air and fuel inlet chamber extending normal to the longitudinal axis thereof and secured to and spaced from said cover and subdividing said air and fuel inlet chamber into a tertiary air inlet compartment and a substantially unobstructed primary air and fuel inlet compartment, said plate having a central orifice opening concentrically to said primary air and fuel compartment, means for gravitationally introducing slag-forming particle fuel substantially tangentially into said primary air and fuel compartment at a position between the opposite ends thereof, means for introducing a high velocity stream of primary air substantially tangentially into said primary air and fuel compartment at a location between the opposite ends thereof and separate from the point of fuel entry and effecting a whirling path of travel therein with the incoming fuel particles along the circumferential wall of said primary air and fuel compartment, means for introducing a stream of secondary air into said combustion chamber tangentially to the circumferential wall thereof at a location between the point of fuel entry and the gas outlet, means for introducing a stream of tertiary air into said tertiary air compartment and effecting a flow therethrough to and through said orifice and primary air and fuel compartment inwardly and axially of and separate from the streams of primary air and fuel entering said primary air and fuel inlet compartment, and a slag outlet in the lower part of said combustion chamber.

6. A cyclone furnace having Walls defining a combustion chamber of substantially circular cross-section, fluid cooling means for said walls, means forming a restricted gas outlet at one end of said chamber, means forming an air and fuel inlet chamber of substantially circular crosssection and of smaller diameter than and opening at one end into the opposite end of said combustion chamber, a cover pivotally connected to and normally closing the opposite end of said air and fuel inlet chamber, a circular plate in said air and fuel inlet chamber extending normal to the longitudinal axis thereof and secured to and spaced from said cover and subdividing said air and fuel inlet chamber into a tertiary air inlet compartment and a substantially unobstructed primary air and fuel inlet compartment, said plate having a central orifice opening concentrically to said primary air and fuel compartment, means for gravitationally introducing slag-forming particle fuel substantially tangentially into said primary air and fuel compartment at a position between the opposite ends thereof, means introducing a high velocity stream of primary air tangentially into said primary air and fuel compartment in the same angular direction as the incoming fuel at a location between the opposite ends thereof and separate from the point of fuel entry and elfecting a whirling path of travel therein with the incoming fuel particles along the circumferential wall of said primary air and fuel compartment, wear blocks lining the circumferential wall and extending longitudinally of said primary air and fuel compartment and each having an arc-shaped inner surface so formed that its leading edge with respect to the whirling direction of the primary air and fuel projects inwardly of the primary air and fuel inlet compartment a slightly greater distance than the trailing edge of the next adjacent downstream block to minimize wear of the biocks, means for introducing a stream of secondary air into said combustion chamber tangentially to the circumferential wall thereof at a location between the point of fuel entry and the gas outlet, means for introducing a stream of tertiary air into said tertiary air compartment and effecting a flow therethrough to and through said orifice and primary air and fuel compartment inwardly and axially of and separate from the streams of primary air and fuel entering said air and fuel inlet chamber, and a slag outlet in the lower part of said combustion chamber.

7. A fuel burner comprising means forming a substantially unobstructed air and fuel inlet chamber of substantially circular cross-section open at one end and closed at its opposite end, means for introducing a low velocity stream of slag-forming particle fuel into said air and fuel inlet chamber at a position between the opposite ends thereof, means for introducing a high velocity stream of air tangentially into said air and fuel inlet chamber at a location between the opposite ends thereof and separate from the point of fuel entry and effecting a whirling path of travel therein with the incoming fuel particles along the circumferential wall'of said air and fuel inlet chamber, and means for introducing another stream of air into the opposite end portion of said air and fuel inlet chamber at a position inwardly and axially of and separate from the streams of fuel and high velocity air entering said air and fuel inlet chamber.

8. A fuel lburner comprising means forming an air and fuel inlet chamber of substantially circular cross section open at one end and closed at its opposite end, a plate in said chamber at a position intermediate the opposite ends thereof subdividing said chamber into a first air inlet compartment and a second air and fuel inlet compartment and formed with an orifice opening from the first compartment to the second compartment, means for introducing slag-forming particle fuel into said second compartment between the opposite ends thereof, means for introducing a high velocity stream of air tangentially into said second compartment at a location between the opposite ends thereof and separate from the point of fuel entry and effecting a whirling path of travel therein with the incoming fuel particles along the circumferential Wall of said second compartment, and means for introducing a stream of air into said first compartment and efiecting a flow therethrough to and through said orifice and second compartment inwardly and axially of the streams of fuel and high velocity air entering said second compartment.

References Cited by the Examiner UNITED STATES PATENTS 858,640 7/07 Welles 110-28 1,373,776 4/21 Taylor 1l028 1,762,505 6/30 Burg 1l028 X 2,357,301 9/44 Bailey et a1. 1l028 2,594,312 4/52 Kerr et al 1l028 2,822,766 2/58 McCullough 1l028 2,982,235 5/61 Gram et a1 1l028 FOREIGN PATENTS 709,685 6/54 Great Britain.

JAMES W. WESTHAVER, Primary Examiner.

PERCY L. PATRICK, FREDERICK L. MATTESON,

111., ROBERT A. OLEARY, Examiners. 

1. A CYCLONE FURNACE HAVING WALLS DEFINING A COMBUSTION CHAMBER OF SUBSTANTIALLY CIRCULAR CROSS-SECTIONS, FLUID COOLING MEANS FOR SAID WALLS, MEANS FORMING A RESTRICTED GAS OUTLET AT ONE END OF SAID CHAMBER, MEANS FORMING A SUBSTANTIALLY UNOBSTRUCTED AIR AND FUEL INLET CHAMBER OF SUBSTANTIALLY CIRCULAR CROSS-SECTION AMD OF SMALLER DIAMETER THAN AND OPENING AT ONE END INTO THE OPPOSITE END OF SAID COMBUSTION CHAMBER, MEANS FOR INTRODUCING A LOW VELOCITY STREAM OF SLAG-FORMING PARTICLE FUEL INTO SAID AIR AND FUEL INLET CHAMBER AT A POSITION BETWEEN THE OPPOSITE ENDS THEREOF, MEANS FOR INTRODUCING A HIGH VELOCITY STREAM OF PRIMARY AIR TANGENTIALLY INTO SAID AIR FUEL INLET CHAMBER AT A LOCATION BETWEEN THE OPPOSITE ENDS THEREOF AND SEPARATE FROM THE POINT OF FUEL ENTRY AND EFFECTING A 